Molecular characterization of Osh6p, an oxysterol binding protein homolog in the yeast Saccharomyces cerevisiae

Wang, Penghua, Duan, Wei, Munn, Alan L. and Yang, Hongyuan 2005, Molecular characterization of Osh6p, an oxysterol binding protein homolog in the yeast Saccharomyces cerevisiae, FEBS journal, vol. 272, no. 18, pp. 4703-4715.

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Title Molecular characterization of Osh6p, an oxysterol binding protein homolog in the yeast Saccharomyces cerevisiae
Formatted title Molecular characterization of Osh6p, an oxysterol binding protein homolog in the yeast Saccharomyces cerevisiae
Author(s) Wang, Penghua
Duan, Wei
Munn, Alan L.
Yang, Hongyuan
Journal name FEBS journal
Volume number 272
Issue number 18
Start page 4703
End page 4715
Publisher Blackwell Publishing Ltd.
Place of publication London, England
Publication date 2005-08-24
ISSN 1742-464x
1742-4658
Keyword(s) OSBP
OSH
Osh6p
oxysterol-binding protein
sterol homeostasis
Summary Oxysterol binding protein (OSBP) and its homologs have been shown to regulate lipid metabolism and vesicular transport. However, the exact molecular function of individual OSBP homologs remains uncharacterized. Here we demonstrate that the yeast OSBP homolog, Osh6p, bound phosphatidic acid and phosphoinositides via its N-terminal half containing the conserved OSBP-related domain (ORD). Using a green fluorescent protein fusion chimera, Osh6p was found to localize to the cytosol and patch-like or punctate structures in the vicinity of the plasma membrane. Further examination by domain mapping demonstrated that the N-terminal half was associated with FM4-64 positive membrane compartments; however, the C-terminal half containing a putative coiled-coil was localized to the nucleoplasm. Functional analysis showed that the deletion of OSH6 led to a significant increase in total cellular ergosterols, whereas OSH6 overexpression caused both a significant decrease in ergosterol levels and resistance to nystatin. Oleate incorporation into sterol esters was affected in OSH6 overexpressing cells. However, Lucifer yellow internalization, and FM4-64 uptake and transport were unaffected in both OSH6 deletion and overexpressing cells. Furthermore, osh6Δ exhibited no defect in carboxypeptidase Y transport and maturation. Lastly, we demonstrated that both the conserved ORD and the putative coiled-coil motif were indispensable for the in vivo function of Osh6p. These data suggest that Osh6p plays a role primarily in regulating cellular sterol metabolism, possibly stero transport.
Language eng
Field of Research 110104 Medical Biochemistry: Lipids
HERDC Research category C1.1 Refereed article in a scholarly journal
Copyright notice ©2005, FEBS
Persistent URL http://hdl.handle.net/10536/DRO/DU:30009160

Document type: Journal Article
Collection: School of Medicine
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